Multi-position lock for trigger switch



July 4, 1967 E. v. SAHRBACKER MULTI-POSITION LOCK FOR TRIGGER SWITCH 2 Sheets-Sheet 1 Filed Nov. 5, 1965 INVENTOR. fan/4e L flw/RaAc/m? BY S ATTORNEY E July 4, 1967 E. v. SAHRBACKER MULTI-POSITION LOCK FOR TRIGGER SWITCH 2 Sheets-Sheet 2 Filed Nov. 5, 1965 R F. m m w M am a k w w W $5 Q MN 5 Na .IHH %W \M W 3 mi Q mm a mm w United States Patent tion of Connecticut Filed Nov. 5, 1965, Ser. No. 506,499 12 Claims. (Cl. 200157) This invention relates to electric switches and, more particularly, to a multi-speed switch having a trigger element that is positionable into separate locked locations for operation at different fixed speeds.

In providing variable speed electrical tools such as piston-grip hand drills and the like, the speed of the motor driven tool is controlled by a finger operated triggerelement which is movable at will in finitely located steps between low and high speed operation. Since human finger control may not be sufficiently stable and can be subject to fatigue, it is desirable, in some operations, to set the trigger switch at a selected speed at wh1ch the tool may continue to operate Without continuing finger control.

According to the present invention, a variable speed switch having finger operated trigger control is provided with novel indexing means for establishing at least two different predetermined operational speeds for the tool drive motor.

A salient feature of the invention is the provision of a simple mechanism for locking the trigger of the switch in either of two separate positions intermediate the low and maximum speeds, the improved mechanism be ng operable by self-indexing means in the trigger itself acting in conjunction with a thumb depressible yieldable element whereby the locking and unlocking of the trigger may be accomplished by the same hand which holds the tool in Its working position. Although the device of the present invention may be utilized in conjunction with infinitely variable switches, it may also be used for the =operat1on of progressive step switches having a limited number of operating positions.

Still other objects and advantages of the invention will be apparent from the specification.

The features of novelty which are believed to be characteristic of the invention are set forth herein and will best be understood, both as to their fundamental principles and as to their particular embodiments, by reference to the specification and accompanying drawings, in which:

FIGURE 1 is a side elevation of a piston-grip electri cally operated hand tool such as a drill, incorporating the switch and trigger control of the present invention in the piston-grip portion thereof, some parts being shown in phantom outline;

FIGURE 2 is an enlarged fragmentary side view of the switch and trigger mechanism shown in outline in FIG- URE 1;

FIGURE 3 is a front view of the device shown in FIG- URE 2;

FIGURE 4 is a reverse side view of the device shown in FIGURE 2;

FIGURE 5 is a greatly enlarged top view taken on line 5-5 of FIGURE 2;

FIGURE 6 is a still further enlarged side view similar to FIGURE 2, showing some parts in section, some parts in phantom outline, and some parts broken away;

FIGURE 7 is a view taken on line 77 of FIG- URE 6;

FIGURE 8 is a fragmentary view taken on line 8-8 of FIGURE 6, showing the trigger in the off position;

FIGURE 9 is similar to FIGURE 8, but showing the trigger locked in a first operating position; and

3,329,789 Patented July 4, 1967 FIGURE 10 is similar to FIGURES 8 and 9, but showing the trigger locked in a second operating position.

Referring now to the drawings in detail, a typical hand tool such as a piston-grip drill, generally designated 11, is shown in FIGURE 1, said drill being operated by an electric motor, not shown, which rotates a clutch 12 within which is mounted a drill bit 13 or the like.

Drill 11 has a hollow piston-grip handle 14 within which is mounted a switch case 16 containing a variable switch, not shown, connected to a suitable power source, not shown, by means of cable 17, said switch, in turn, being connected to the electric drill motor by suitable electrical circuitry well known in the art. The switch in case 16 controls the speed of the electric motor from an off condition to an on condition and thence from low speed to high speed in infinite gradients. The switch has a suitable infinitely variable current or voltage control such as variable resistor, potentiometer, or the like having a movable control element for varying the power supplied to the tool motor. Variable switches of this type are well known in the art.

The open side portion of switch case 16, which is made of suitable insulating material, is connected to a sheet metal rectangular bracket 18 by suitable means, said bracket having a central, rectangular aperture 19 which is positioned over the open side of said switch case. Bracket 18 is fastened to the lower end portion of a vertical channel track element 21 by means of spaced apart rivets 22. The upper portion of track element 21 has an integrally formed lug 23 having a plurality of apertures 24 for attachment by way of rivets or studs to the interior of handle 14.

Track element 21 is made of sheet metal and is bent to form an elongated channel 26 within which an elongated actuator 27 is reciprocably movable. The lower end of actuator 27 has an integrally formed laterally extending lug 28 which engages a slot 29 of slider element 31 movable slidably and reciprocably across the opening of case 16. Slider 31, made of suitable insulating material, has an integrally formed boss 32 which extends into the interior of case 16 to engage and operate the variable or stepping control of the motor switch.

The upper portion of track element 21 has an enlarged V-shaped channel formed of sloping forward wall 36 and integrally formed spaced apart side walls 37 and 38 between which a plurality of trigger components operate.

Mounted between the forward portions of walls 37 and 38 near the upper ends thereof is a pin 39 upon which is pivotally mounted a trigger element, generally designated 41, formed of a unitary piece of sheet metal having two spaced apart side walls 42 and 43 and an integrally formed forward end wall 44 upon which the operators finger bears.

Mounted between trigger walls 42 and 43, at their upper and rearward portions, and spaced apart from pin 39 is a second pin 46 upon which the upper end of actuator 27 is pivotally mounted. The upper edges of trigger walls 42 and 43 each have small notches 47 and 48, respectively, formed therein intermediate pins 39 and 46, said notches supporting between them a third pin 49. Connected to pin 49 is one end of a spring 51, the other end of which is hooked through aperture 52 in track element 21 intermediate the ends thereof. Spring 51, under tension, normally urges pin 49 downwardly to cause trigger 41 to pivot into a forward off position, as shown in FIGURES 1, 2 and 3, while at the same time actuator 27 is urged into its extreme downward position where normally the switch elements in case 16 are in the open circuit condition. The downward motion of actuator 27 is limited by pin 46 abutting the top edges of Walls 37 and 38.

Upon retraction of trigger 41 against the action of 3 spring 51, the resulting pivoting motion raises pin 46 thereby causing actuator 27 and slider 31 to move upwardly whereby the switch assumes a closed circuit condition and its electric power or current transmitting capacity may be varied to the extent that trigger 41 is retracted.

Near the upper ends of walls 37 and 38 there are formed axially oriented apertures 56 and 57, respectively, which slidably accommodate a shaft 58, said shaft having an integrally formed outwardly extending head 59 whose diameter is somewhat larger than that of said shaft.

Mounted around shaft 58 is spring 61, one end of which bears against the outer surface of wall 37, the other end of which bears against the interior wall of a circular recess 62 formed at the inner portion of head 59. The action of spring 61 normally urges shaft 58 and head 59 to move outwardly, said movement being limited by an integral flange 63 on the free end of shaft 58 which bears against the outer surface of wall 3 8.

Wall 43 of trigger 41 has an elongated slanting apert-ure 66 which is somewhat wider than the outside diameter of flange 63 on shaft 58 whereby the latter can be caused to protrude through said aperture when head 59 is pressed against the action of spring 61.

Normally, when trigger 41 is in the released and off circuit position as shown in FIGURES 2, 6 and 8, for example, wall 43 overlaps aperture 57 in wall 38, thereby preventing any depression of shaft 58 against the action of spring 61. When trigger 41 is retracted to an intermediate position 1 as shown in FIGURES 6 and 9, a portion of aperture 61 becomes aligned with aperture 57 thereby permitting head 59 to be depressed against the action of spring 61 to cause the free end of shaft 58 to extend through aperture 66.

When trigger 41 is released at this time, flange 63 of shaft 58 engages the upper edge of aperture 66 to lock said trigger in the first position whereby the tool motor operates at a selected predetermined fixed speed without the necessity for maintaining the trigger position by finger operation. When it is desired to turn off the tool motor, slight retraction of trigger 41 causes flange 63 to be released from the edge of aperture 66 whereby shaft 58 is automatically withdrawn therefrom under the action of spring 61 to its non-operating position as shown in FIGURE 8. Upon release of trigger 41, spring 51 operates to return said trigger to its off position and to depress actuator 27 and slider 31 into an off circuit condition for the switch elements in case 16.

Formed in wall 42 of trigger 41 is an elongated aperture 71 having a small upper portion and a somewhat larger lower portion. The smaller portion of aperture 71 freely bypasses shaft 58 during the pivoting action of trigger 41. That part of wall 42 surrounding the lower larger portion of aperture 71 has an outwardly extending flange 72 which engages an outwardly extending rib 73 on the inner end of head 59 when the latter is depressed against the action of spring 61 and when trigger 41 is retracted to a second operating position as shown in FIGURES 6 and 10. In position 2 of trigger 41, the latter is now locked in a location where the tool motor operates at a second selected predetermined fixed speed without the necessity for maintaining said trigger position by finger operation.

When it is desired to turn off the tool motor from its second fixed position, slight retraction of trigger 41 causes rib 73 to be released from flange 72 whereby head 59 is automatically withdrawn and moved outwardly under the action of spring 61 to the non-operating position as shown in FIGURE 8. Upon release of trigger 41, spring 51 operates to return said trigger to its off position and to depress actuator 27 and slider 31 into an off circuit condition for the switch elements in case 16.

In both position 1 and position 2 of trigger 41,

,4 actuator 27 and slider 31 are located in positions where the circuit elements in switch case 16 are operated to cause the tool motor to run at different respective predetermined speeds.

In operation, when the operators hand grasps the pistol grip 14 of tool 11, the forefinger is in a natural position to operate trigger 44 while the operators thumb is in a natural position to manipulate head 59 to depress the latter into the selected positions for locking trigger 41 as shown in FIGURES 9 and 10*. In the embodiment illustrated herein, the thumb operated head 59 and shaft 58 move in a direction laterally in respect of or substantially perpendicular to the direction of movement of trigger 41.

By utilizing the locking device as described hereinbefore, the operator is relieved of the fatiguing task of attempting to maintain the trigger in a desired constant speed location. At any desired time, the operator may slightly retract trigger 41 to permit flange 63 of shaft 58 or rib 72 of head 59 to be automatically released in order to turn off the tool motor. Optionally, the operator may dispense with the manipulation of head 59 and utilize finger control on trigger 41 for establishing and maintaining different motor speeds, at will.

By arranging for a thumb control element such as embodied in the unitary combination of shaft 58 and head 59 where these component parts are of different diameter and where each of said components is engaged selectively by the trigger element at different pivoted locations thereof, it is now possible to provide a multiplex operation of the tool motor by a device made of simple, stamped parts and which is easily and conveniently manipulated by the tool operator.

In some embodiments, flange 63 and rib 73 may be omitted from pin 58 and head 59, respectively, since trigger spring 51 may be provided with sufli-cient power to cause the frictional engagement of the edges of apertures 66 and 71 with said pin and said head to maintain the respective parts in locked condition.

What is claimed is:

1. A trigger switch apparatus comprising a support, a trigger pivotally mounted on said support, a switch actuator element mounted pivotally on said trigger and movable thereby, means normally urging said trigger and said actuator yieldably into an off position, means on said support movable into either of first and second positions, said movable means in its first position engaging and locking said trigger into a first switch operating position and in its second position engaging and locking said trigger into a second switch operating position.

2. Apparatus according to claim 1 wherein said movable means comprises a pin slidably mounted on said support, and further comprising a spring normally disengaging said pin from said trigger, a first portion of said pin engaging a first portion of said trigger when the latter is retracted into said first position, a second portion of said pin engaging a second portion of said trigger when the latter is retracted into said second position.

3. Apparatus according to claim 1 and further comprising a switch case mounted on said support, said actuator being movable relative to the interior of said case for operating the switch elements contained therein.

4. A trigger switch apparatus comprising a support, a trigger pivotally mounted on said support, said trigger normally being yieldably spring biased to an off position and retractable to an infinite gradient of switching positions, a pin mounted on said support and movable laterally in respect of said trigger, a first portion of said pin engaging a first portion of said trigger to lock the latter in a first switching position, a second portion of said pin engaging a second portion of said trigger to lock the latter in a second switching position.

5. Apparatus according to claim 4 and further comprising a spring between said support and said pin normally urging said pin into disengagement from said trigger.

6. Apparatus according to claim wherein said trigger comprises first and second spaced apart walls movable past respective sides of said support and wherein said pin engages one of said walls for locking said trigger in said first position and engages the second of said walls for locking said trigger in said second position.

7. Apparatus according to claim 6 and further comprising an aperture in said support, said pin being slidably movable through said aperture, an aperture in the first trigger wall, an aperture in the second trigger Wall, one portion of said pin having a predetermined diameter and engaging the edge of said aperture in said first wall to lock said trigger in said first position, another portion of said pin having a somewhat larger diameter and engaging the edge of said aperture in said second wall to lock said trigger in said second position.

8. Apparatus according to claim 7 wherein said trigger and said pin are located in relation to each other for manipulation of said trigger by the forefinger and of said pin by the thumb of the hand by the operator.

9. Apparatus according to claim 6 wherein slight retraction of said trigger when the latter is in either of said first or second positions permits the pin spring to disengage said pin from said trigger.

10. A trigger switch apparatus comprising a support, said support being shaped to form an elongated channel, a trigger pivot-ally mounted on said support, said trigger normally being yieldably spring biased to an off position and retractable to an infinite gradient of switching positions, a pin mounted on said support and movable laterally in respect of said trigger, said pin being movable into either of two positions for releasably locking said trigger in either of a first and second retracted switching position relative to said support, a switch actuator m0unted pivotally on said trigger and movable reciprocably within said channel upon the pivoting action of said trigger, and a switch case mounted on said support, said actuator communicating with the interior of said case.

11. Apparatus according to claim 10 and further comprising a first spring connected between said trigger and said support, and a second spring connected between said pin and said support.

12. Apparatus according to claim 10, wherein said pin comprises first and second portions, said first portion upon partial movement of said pin engaging said trigger in said first position, said second portion of said pin upon further movement of said pin engaging said trigger in said second position.

References Cited UNITED STATES PATENTS 3/1960 Cranmore 200-157 8/1960 Park et al 200157 

4. A TRIGGER SWITCH APPARATUS COMPRISING A SUPPORT, A TRIGGER PIVOTALLY MOUNTED ON SAID SUPPORT, SAID TRIGGER NORMALLY BEING YIELDABLY SPRING BIASED TO AN "OFF" POSITION AND RETRACTABLE TO AN INFINITE GRADIENT OF SWITCHING POSITIONS, A PIN MOUNTED ON SAID SUPPORT AND MOVABLE LATERALLY IN RESPECT OF SAID TRIGGER, A FIRST PORTION OF SAID PIN ENGAGING A FIRST PORTION OF SAID TRIGGER TO LOCK THE LATTER IN A FIRST SWITCHING POSITION, A SECOND PORTION OF SAID 